Absolute strain measurements made with fiber Bragg grating sensors

Abstract

A strain sensor system based on optical fiber Bragg gratings (FBGs) is proposed with a new matched-filter design. The strain variation on the sensor FBG is continuously followed and matched by a filter FBG by use of a feedback control loop that produces an identical strain condition on the filter FBG. The matched strain on the filter FBG is then determined from the resonance vibration of the fiber piece embedding the filter FBG. The implementation and the performance of the proposed system are described. It is demonstrated that the proposed system can distinguish strain variation on the sensor FBG with resolution of one microstrain.

Fiber optic-based sensors design to test concrete structures

“…Hence, when only the wavelength shift is measured, the effect of both parameters cannot be distinguished. Nevertheless, a lot of works have been carried out during the last years in order to discriminate these parameters [8][9][10][11][12][13][14] .…”

“…Thus, Bragg grating sensors [2][3][4][5][6][7][8][9][10][11][12][13][14] , chirped grating sensors [15][16][17][18][19][20][21][22] , long period grating sensors [23][24][25][26][27][28][29] and interferometric configurations based on gratings [30][31][32][33][34][35][36] are examples of fiber optic sensors which had been proposed and developed to test and measure axial strain, temperature changes and transverse load in structures. In particular, Fiber Bragg Gratings (FBG's) are simple and easy to manufacture [31][32][33] and have all the previously commented advantages regarding optical sensors.…”

“…These sensors are designed to permit the measurement of loads and tensions applied to the structure, just as the temperature, humidity and pH of the concrete at the measurement point. The strain of the structure can be measured by means of widely-known fiber Bragg grating techniques [8][9][10][11][12][13][14] , which involves wavelength multiplexing and optical spectrum analysis. Moreover, these techniques are able to distinguish between the influence of load and temperature.…”

Study on weigh-in-motion system based on chirped fiber gratings

“…The FBG sensor is resistant to humidity, erosion and electromagnetic interference, and has high accuracy, good reproducibility, so it is got more attention than ever before [2,3]. In the fibre grating distributed sensing system, normally, people use wavelength scanning demodulator or interferometer to detect the signal [4][5][6], but the cost is so expensive and the demodulating speed is not so fast that it is hardly used in practical application of dynamic weighing field.…”

Fiber Bragg grating multichemical sensor

“…A few of these include bridge and mine stress measurements, marine vehicle pressures, and aircraft stress assessment. [2][3][4][5] Use of FBGs as chemical sensors is less prevalent. In our applications, a polymer coating is applied to the fiber so that interaction with target chemicals produces a swelling of the polymer and subsequent straining of the fiber and FBG contained within.…”